Switch and Method for Guaranteeing Quality of Service of Multi-Tenant Cloud Service and System Having the Same Switch

1. A dynamic virtual flow switch comprising: a switch flow agent configured to receive and store virtual machine QOS information about each of a plurality of virtual machines operating in a plurality of computer servers and flow QOS information about a flow generated by the virtual machine from a virtual flow controller; and a flow processing unit configured to receive the flow generated by the virtual machine and determine a QOS priority of the flow based on the stored virtual machine QOS information of the virtual machine and flow QOS information of the flow, wherein the dynamic virtual flow switch is plural in number, and the plurality of dynamic virtual flow switches are connected over an intranet or the Internet, wherein the dynamic virtual flow switch is configured to calculate a total sum of bandwidth usages of the flows generated by the plurality of virtual machines, wherein the dynamic virtual flow switch is configured to compare the total sum of flow bandwidth usages of the flows with a network bandwidth between the dynamic virtual flow switch and the computer server, wherein, when the total sum of flow bandwidth usages is greater than the network bandwidth, the dynamic virtual flow switch compares a flow bandwidth usage of a flow generated by each of the plurality of virtual machines with a bandwidth setting value of the virtual machine, wherein, when the flow bandwidth usage is greater than the bandwidth setting value of the virtual machine, the dynamic virtual flow switch compares a flow bandwidth usage generated by each of flows generated by the plurality of virtual machines with a bandwidth setting value of the flow, and wherein, when the flow bandwidth usage is greater than the bandwidth setting value of the flow, the dynamic virtual flow switch determines a QOS priority for the flow based on the virtual machine QOS information about the virtual machine that has generated the flow and the flow QOS information about the flow.

2. The dynamic virtual flow switch of claim 1 , further comprising at least one of an L2 switch and an L3 switch, wherein the dynamic virtual flow switch is connected to the plurality of computer servers through at least one of the L2 switch and L3 switch.

3. The dynamic virtual flow switch of claim 1 , wherein the virtual machine QOS information comprises at least one of real-time/non-real-time attribute information, high/low bandwidth requirement information, delay sensitive/non-sensitive service attribute information, service traffic directionality information, and virtual machine bandwidth information about a service provided by the virtual machine.

4. The dynamic virtual flow switch of claim 1 , wherein the flow QOS information comprises at least one of real-time/non-real-time attribute information, high/low bandwidth requirement information, delay sensitive/non-sensitive service attribute information, and service traffic directionality information.

5. The dynamic virtual flow switch of claim 1 , wherein, when the virtual machine is generated by a virtual machine manager, the virtual machine QOS information is set by the virtual machine manager and delivered to the virtual flow controller.

6. The dynamic virtual flow switch of claim 1 , wherein, when flow traffic is generated by the virtual machine, the generated flow traffic is delivered to the virtual flow controller and the flow QOS information about the flow is set by the flow controller.

7. The dynamic virtual flow switch of claim 1 , wherein the flow processing unit determines a QOS priority of the flow such that the flow is preferentially processed if the flow has flow QOS information corresponding to at least one of the virtual machine QOS information about the virtual machine that has generated the flow.

8. The dynamic virtual flow switch of claim 1 , wherein the switch flow agent periodically receives and updates the virtual machine QOS information and the flow QOS information from the virtual flow controller.

9. A network system comprising: a virtual machine manager configured to generate a plurality of virtual machines and set virtual machine QOS information about each of the generated plurality of virtual machines; a virtual flow controller configured to receive and store the virtual machine QOS information about each of the plurality of virtual machines from the virtual machine manager and set and store flow QOS information about a flow generated by the virtual machine; a plurality of computer servers configured to execute at least one of the plurality of virtual machines generated by the virtual machine manager and have an edge flow agent for forwarding a new traffic to the virtual flow controller when the new flow traffic is generated by the virtual machine; and a dynamic virtual flow switch configured to receive and store the virtual machine QOS information and the flow QOS information from the virtual flow controller and when a flow is received from each of the plurality of computer servers, determine a QOS priority of the flow based on the stored virtual machine QOS information and flow QOS information and process the flow.

10. The network system of claim 9 , wherein the dynamic virtual flow switch is plural in number, and the plurality of dynamic virtual flow switches are connected over an intranet or the Internet.

11. The network system of claim 9 , wherein the dynamic virtual flow switch is connected with the plurality of computer servers through at least one of an L2 switch and an L3 switch.

12. The network system of claim 9 , wherein the virtual machine QOS information comprises at least one of real-time/non-real-time attribute information, high/low bandwidth requirement information, delay sensitive/non-sensitive service attribute information, service traffic directionality information, and virtual machine bandwidth information about a service provided by the virtual machine.

13. The network system of claim 9 , wherein the flow QOS information comprises at least one of real-time/non-real-time attribute information, high/low bandwidth requirement information, delay sensitive/non-sensitive service attribute information, and service traffic directionality information.

14. The network system of claim 9 , wherein the dynamic virtual flow switch determines a QOS priority of the flow such that the flow is preferentially processed if the flow has flow QOS information corresponding to at least one of the virtual machine QOS information about the virtual machine that has generated the flow.

15. A method of managing QOS for flows at a dynamic virtual flow switch, the flows being generated by a plurality of virtual machines operating in a plurality of computer servers and the dynamic virtual flow switch being connected with the plurality of computer servers to receive and process the flows, the method comprising: calculating a total sum of bandwidth usages of the flows generated by the plurality of virtual machines; comparing the total sum of flow bandwidth usages of the flows with a network bandwidth between the dynamic virtual flow switch and the computer server; when the total sum of flow bandwidth usages is greater than the network bandwidth, comparing a flow bandwidth usage of a flow generated by each of the plurality of virtual machines with a bandwidth setting value of the virtual machine; when the flow bandwidth usage is greater than the bandwidth setting value of the virtual machine, comparing a flow bandwidth usage generated by each of flows generated by the plurality of virtual machines with a bandwidth setting value of the flow; and when the flow bandwidth usage is greater than the bandwidth setting value of the flow, determining a QOS priority for the flow based on the virtual machine QOS information about the virtual machine that has generated the flow and the flow QOS information about the flow.

16. The method of claim 15 , wherein the determining of the QOS priority for the flow comprises determining the QOS priority of the flow such that the flow is preferentially processed if the flow has flow QOS information corresponding to at least one of the virtual machine QOS information about the virtual machine that has generated the flow.